This invention relates to an electronic control unit for use e.g. in a vehicle brake hydraulic pressure control system, and a method for manufacturing the same.
Typically, vehicle brake hydraulic pressure control systems having electronic control functions comprise a hydraulic unit including a pump, a motor for driving the pump, and solenoid valves for controlling hydraulic pressure, and an electronic control unit. The electronic control unit includes a circuit board carrying control circuits and mounted in and held in position by a case. A typical such brake hydraulic pressure control system is disclosed in JP patent publication 2006-27528A.
The circuit board of such an electronic control unit carries various functional elements (electronic parts) forming control circuits. A large number of bus bars are also connected to the circuit board to electrically connect its electrical circuits to the motor, solenoid valves for controlling hydraulic pressure and other parts of the hydraulic unit. The bus bars are fixed to the case, which is made of resin, by insert molding. In the conventional arrangement, as disclosed in the above patent publication 2006-27528A, with terminal portions of the bus bars arranged in a row, the terminal portions are passed through the circuit board and soldered to terminal connecting portions of the electrical circuits on the circuit board.
In this conventional arrangement, as disclosed in the above patent publication 2006-27528A, because the terminal portions of the bus bars are arranged in a single row and connected to the electrical circuits on the circuit board, the adjacent terminal portions have to be arranged with a sufficiently large pitch in order to prevent short-circuiting therebetween. Thus, a large soldering space is necessary to connect the bus bars, which correspondingly reduces the space on the circuit board for mounting functional elements.
The smaller the soldering space for the bus bars, the larger the mounting space on the circuit board for functional elements. This makes it possible to mount a larger number of functional elements, thereby performing more sophisticated control, or if no such sophisticated control is necessary, it is possible to reduce the size of the circuit board, and thus the size of the electronic control unit including such a circuit board, as well as the size of the entire device using such an electronic control unit.